//
//  DownLoadManager.m
//  DownLoad_demo
//
//  Created by muji on 16/3/18.
//  Copyright © 2016年 muji. All rights reserved.
//

#import "DownLoadManager.h"

@interface DownLoadManager() <NSURLSessionDataDelegate,NSURLSessionDownloadDelegate>



@property (nonatomic,strong) NSString *filePath;

@end

@implementation DownLoadManager

+ (instancetype)shared
{
    static DownLoadManager *manager = nil;
    
    static dispatch_once_t onceToken;
    dispatch_once(&onceToken, ^{
        manager = [[DownLoadManager alloc] init];
    });
    
    return manager;
}

- (void)selectDownLoadBtn:(id<DownLoadDelegate>)delegate
                     with:(NSString *)filePath
                     with:(NSString *)url
{
    self.delegate = delegate;
    self.url = url;
    self.filePath = filePath;
    
    [self start];
    
//    if (self.task == nil) { // 开始（继续）下载
//        if (self.resumeData) { // 恢复
//            [self resume];
//        } else { // 开始
//            [self start];
//        }
//    } else { // 暂停
//        [self pause];
//    }
}


- (NSURLSession *)session
{
    if (!_session) {
        NSURLSessionConfiguration *cfg = [NSURLSessionConfiguration defaultSessionConfiguration];
        self.session = [NSURLSession sessionWithConfiguration:cfg delegate:self delegateQueue:[NSOperationQueue mainQueue]];
    }
    return _session;
}


- (IBAction)download:(UIButton *)sender {
    // 按钮状态取反
    sender.selected = !sender.isSelected;
    
    if (self.task == nil) { // 开始（继续）下载
        if (self.resumeData) { // 恢复
            [self resume];
        } else { // 开始
            [self start];
        }
    } else { // 暂停
        [self pause];
    }
}

/**
 *  从零开始
 */
- (void)start
{
    // 1.创建一个下载任务
    NSURL *url = [NSURL URLWithString:self.url];
    self.task = [self.session downloadTaskWithURL:url];
    // 2.开始任务
    [self.task resume];
}

/**
 *  恢复（继续）
 */
- (void)resume
{
    // 传入上次暂停下载返回的数据，就可以恢复下载
    self.task = [self.session downloadTaskWithResumeData:self.resumeData];
    
    // 开始任务
    [self.task resume];
    
    // 清空
    self.resumeData = nil;
}

/**
 *  暂停
 */
- (void)pause
{
    __weak typeof(self) vc = self;
    [self.task cancelByProducingResumeData:^(NSData *resumeData) {
        //  resumeData : 包含了继续下载的开始位置\下载的url
//        vc.resumeData = resumeData;
        vc.task = nil;
    }];
}

#pragma mark - NSURLSessionDownloadDelegate
- (void)URLSession:(NSURLSession *)session downloadTask:(NSURLSessionDownloadTask *)downloadTask
didFinishDownloadingToURL:(NSURL *)location
{
    NSString *caches = [NSSearchPathForDirectoriesInDomains(NSCachesDirectory, NSUserDomainMask, YES) lastObject];
    // response.suggestedFilename ： 建议使用的文件名，一般跟服务器端的文件名一致
    NSString *file = [caches stringByAppendingPathComponent:downloadTask.response.suggestedFilename];
    // 将临时文件剪切或者复制Caches文件夹
    NSFileManager *mgr = [NSFileManager defaultManager];
    // AtPath : 剪切前的文件路径
    // ToPath : 剪切后的文件路径
    [mgr moveItemAtPath:location.path toPath:self.filePath error:nil];
    if ([self.delegate respondsToSelector:@selector(downloadFinish:)]) {
        [self.delegate downloadFinish:self.filePath];
    }
}

- (void)URLSession:(NSURLSession *)session downloadTask:(NSURLSessionDownloadTask *)downloadTask
      didWriteData:(int64_t)bytesWritten
 totalBytesWritten:(int64_t)totalBytesWritten
totalBytesExpectedToWrite:(int64_t)totalBytesExpectedToWrite
{
//    NSLog(@"获得下载进度--%@\n%f", [NSThread currentThread],(double)totalBytesWritten / totalBytesExpectedToWrite);
    // 获得下载进度
    if (self.delegate && [self.delegate respondsToSelector:@selector(getDownLoadLegth:)]) {
        [self.delegate getDownLoadLegth:(double)totalBytesWritten / totalBytesExpectedToWrite];
    }
}

- (void)URLSession:(NSURLSession *)session downloadTask:(NSURLSessionDownloadTask *)downloadTask
 didResumeAtOffset:(int64_t)fileOffset
expectedTotalBytes:(int64_t)expectedTotalBytes
{
    
}

- (void)URLSession:(NSURLSession *)session didBecomeInvalidWithError:(NSError *)error
{
    
}

@end
